I have an array HSPACE which is defined inside a python script. I am trying to pass this array to a shell script "arraytest" and execute it from python itself. I am trying with the following piece of code but it doesnt seem to be working:
HSPACE=[0.01, 0.009, 0.008, 0.007]
subprocess.call(["./arraytest"], HSPACE, shell=True)
The content of the shell script is:
#!/bin/bash
for i in ${HSPACE[@]}
do
echo $i
done
The easy answer is to pass each array entry as a literal argv entry:
subprocess.call(['./arraytest'] + [str(s) for s in HSPACE], shell=False)
...thereafter...
#!/bin/bash
printf 'hspace array entry: %q\n' "$@"
Another approach is to pass an array as a NUL-delimited stream on stdin:
p = subprocess.Popen(['./arraytest'], shell=False, stdin=subprocess.PIPE)
p.communicate('\0'.join(str(n) for n in HSPACE) + '\0')
...and, in your shell:
#!/bin/bash
arr=( )
while IFS= read -r -d '' entry; do
arr+=( "$entry" )
done
printf 'hspace array entry: %q\n' "${arr[@]}"
eval to unpack it, I'm hesitant to put that code in an answer and thereby endorse its use. (Though one could also, say, base64-encode a NUL-delimited stream in the environment, but that's just getting silly).
shell=Trueunless you have a compelling reason and know exactly why you're using it; it adds substantial complexity and security exposure.${HSPACE[@]}-- while not useful here because HSPACE isn't inherited (arrays can't be exported through the environment, so it's not just a matter of syntax but feasibility) -- is incorrect syntax to expand an array's contents while keeping the original division between element boundaries; it behaves precisely identically to${HSPACE[*]}, which combines elements of the array with the first character ofIFSand then subjects the result to string-splitting and globbing. To avoid this, you need to quote:"${HSPACE[@]}".evals to array contents, but the shell receiving and evaluating it needs to trust the source of that value, making it a poor practice and prone to creating shell injection vulnerabilities if not done properly).H:0.01 H:0.009 H:0.008 H:0.007 V:1.23 V:4.56is an example of what the latter argv would look like; the shell script could then just iterate over"$@"and assign each item to the correct array based on its prefix.